Wireless nanopore electrodes for analysis of single entities

Area of Science:

• Nanotechnology
• Electrochemistry
• Single-entity analysis

Background:

• Single-entity measurements are crucial for understanding molecular, nanoparticle, and cellular heterogeneity.
• Electrochemical methods offer fast, direct analysis of single entities by probing electron transfer.
• Fabricating reproducible nanoscale electrochemical-sensing interfaces remains a challenge.

Purpose of the Study:

• To present a general, easily implemented protocol for fabricating and utilizing wireless nanopore electrodes (WNEs).
• To enable reproducible electrochemical measurements of single entities at the nanoscale.
• To demonstrate WNE applications in detecting single molecules, analyzing cell metabolism, and discriminating nanoparticles.

Main Methods:

• Fabrication of wireless nanopore electrodes (WNEs) via nanoscale metal deposition at the tip of a nanopipette.
• Utilizing dynamic ionic flow within the nanopore for interfacial redox sensing.
• Construction and characterization of open-type and closed-type WNEs.
• Integration with signal amplification mechanisms for enhanced detection.

Main Results:

• Developed WNEs with controllable interface diameters (30-200 nm).
• Achieved reproducible electrochemical measurements of single entities using WNEs.
• Demonstrated detection of single redox molecules/ions, analysis of single-cell metabolism, and discrimination of single nanoparticles.

Conclusions:

• WNEs offer a highly controllable and reproducible nanointerface for electrochemical sensing.
• The protocol is broadly applicable to single-entity studies in nanomaterials, sensors, and biological systems.
• WNEs provide a cost-effective (~$1-$3) and time-efficient (~10-18 h) solution for nanoscale electrochemical analysis.